Highway crews were conducting blasting operation of a flood project on Colorado Highway 119 in Boulder Canyon. A normal blast brings down about 400 cubic yards of rock. But a blast on Wednesday brought down 8,000 cubic yards. It may take a day or more to clear the roadway which is now closed. CDOT says recent heavy rains may have contributed to the massive rockfall. CDOT is working with the Boulder Valley School District to reroute school buses. Local detours are putting people onto Colorado Highway 72.